Arresting dental caries in preschool children using silver nitrate solution followed by sodium fluoride varnish : a randomised clinical trial

Abstract

A systematic review of clinical trials published in English on remineralising effect of caries with sodium fluoride and silver diamine fluoride among children were performed. Six studies on sodium fluoride were identified and meta-analysis showed that 5% sodium fluoride varnish could remineralise early enamel caries. The overall percentage of remineralised enamel caries was 64%. Five studies on silver diamine fluoride reported that 38% silver diamine fluoride was effective in arresting dentine caries. The overall proportion of arrested dentine caries was 66%. Because silver diamine fluoride was mostly used in China, Japan and Latin America, another systematic review was conducted by searching publications in five languages which were English, Chinese, Japanese, Spanish and Portuguese. Nineteen studies were identified, and meta-analysis found that 38% silver diamine fluoride is effective in arresting dentine caries in primary teeth. The overall percentage of active caries that became arrested was 81%. As silver diamine fluoride was not available in many countries, silver nitrate with sodium fluoride was proposed to use as an alternative strategy to arrest caries. Caries is an infection caused by cariogenic bacteria which demineralise enamel and dentine in the presence of fermentable carbohydrate. Silver nitrate solution has antimicrobial property and sodium fluoride promotes remineralisation. They may be used together for caries arrest. However, there was no clinical trial published in the literature on the effectiveness of using silver nitrate solution and sodium fluoride varnish for caries arrest. Thus, a randomised, double-blind, non-inferiority clinical trial was conducted to compare the effectiveness of 25% silver nitrate solution followed by 5% sodium fluoride varnish with 38% silver diamine fluoride solution (positive control) in arresting dentine caries among kindergarten children when applied semi-annually. Ethics approval was sought from an institutional review board. Healthy 3-year-old children with active cavitated caries were randomly allocated into two groups for treatment with parental consent. Children received either a semi-annual application of 25% silver nitrate solution followed by 5% sodium fluoride varnish, or a semi-annual application of 38% silver diamine fluoride solution followed by a placebo varnish. Caries and oral hygiene status were recorded by a trained examiner at baseline and follow-up examinations. The examiner, children and their caretakers were blinded to the intervention allocation. Questionnaires regarding children抯 oral health-related behaviours and socioeconomic backgrounds were obtained at baseline and 18-month follow-up. Non-inferiority test, independent t-test, chi-square test and logistic regression were performed for data processing. According to the baseline results, risk factors including age of start tooth-brushing, daily snack intake frequency, dental visit experience, birthplace, monthly family income, main caretaker, and mother's education level were associated with the presence of dental caries. The results showed that a semi-annual application of 25% silver nitrate solution followed by 5% sodium fluoride varnish was not worse than 38% silver diamine fluoride in arresting dentine caries among preschool children. The caries-arresting rate was influenced by the child's oral hygiene and the location of the caries surface. This study supports the use of silver nitrate with sodium fluoride as an alternative strategy to arrest caries.